The only commercial process for the production of methanol starts with the generation of synthesis gas containing carbon monoxide and hydrogen. When natural gas is the raw material, synthesis gas can be formed by reacting the methane in the natural gas with carbon dioxide and water over a catalyst at elevated temperatures. The resulting synthesis gas is converted to methanol at high pressures using a suitable catalyst.
Numerous improvements have been made in the methanol process since it was introduced in the 1920's. Nevertheless, this process is handicapped by high capital investment to produce the synthesis gas and by the need to operate the conversion step at elevated pressure to overcome the unfavorable equilibrium conditions.
Certain inefficiencies are inherent in the present process for producing methanol. The process is wasteful of energy in the sense that it first transforms methane in an oxidative reaction to carbon monoxide, which in turn must be reduced to methanol. The direct selective transformation of methane to methanol is therefore a highly desirable goal and one that has been pursued by numerous researchers.
The main problem associated with the direct oxidation of methane to methanol is the unavoidable formation of byproducts including formaldehyde, formic acid, carbon monoxide, and the ultimate oxidation product, carbon dioxide. The challenge therefore has been to identify a catalyst that is highly selective for the formation of methanol. To date, such catalysts as molybdenum and vanadium oxides have been found to be the most effective but still fall short of industrial expectations.
Other applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.